Heat exchangers for vaporizing liquid refrigerant



H. W. KLEIST HEAT EXCHANGERS FOR VAPORIZING LIQUID REFRIGERANT June 3,1958 Filed March 7, 1955 United States Patent HEAT EXCHANGERS FORVAPORIZING LIQUID REFRIGERANT Herman W. Kleist, Hollywood, Ill.,assigner to Dole Refrigerating Company, Chicago, lll., a corporation ofIllinois Application lvlarch 7, 1955, Serial No. 492,435

7 Claims. (Cl. 62.-3)

My invention relates to an improvement in refrigerating means, and hasfor one purpose to provide improved means for controlling the iiow ofvolatile refrigerant from or to a compressor.

Another purpose is to provide means for controlling the temperature ofthe refrigerant as supplied to the condenser from the compressor.

Another purpose is to provide control means for controlling the flow ofrefrigerant from the compressor to the condenser and receiver whichrender valving or restriction of ow unnecessary.

Another purpose is to provide means effective to compensate forvariation in outside ambient temperature, when a flow of volatilerefrigerant is subjected to such variations.

Other purposes will appear from time to time in the course of thespecification and claims.

The present application is a continuation-in-part of my copendingapplication Serial No. 443,759, filed in the United States Patent Officeon July 16, 1954, now Patent No. 2,775,683 of Dec. 2, 1956, for HeatExchangers for Vaporizing Liquid Refrigeran I illustrate my inventionmore or less diagrammatically in the accompanying drawings wherein:

Figure l is a diagrammatic illustration of an embodiment of myinvention;

Figure 2 is an axial section through a heat exchanger indicated inFigure l; and

Figure 3 is a section on the slide 3--3 of Figure 2.

Like parts are indicated by like symbols throughout the specication anddrawings.

Referring to the drawings, 1 generally indicates a compressor in arefrigerating cycle in which, for example, a volatile refrigerant isemployed. 2 indicates a suction return pipe extending from any suitableevaporator or evaporators, not herein shown, to the suction or inletside of the compressor 1. 3 indicates any suitable condenser connectedby a pipe 4 to any suitable receiver 5. 6 indicates a duct or pipe fromthe discharge or pressure side of the compressor 1 to the intake of thecondenser 3. A indicates a heat exchange unit in the pipe 6 which willlater be described in detail. 7 indicates a delivery pipe extending toany suitable evaporator or evaporators, not shown.

It will be understood that, as an example of my invention, I haveillustrated part of a conventional refrigerating cycle in which avolatile refrigerant is delivered as a hot gas from the pressure side ofa compressor, such as the compressor 1, is condensed to a hot liquid,still under pressure, in any suitable condensing means, such as mycondenser 3, and is thereafter delivered, under pressure, as a liquid,along any suitable delivery line to whatever evaporating means areemployed. The volatile refrigerant is evaporated in the evaporator inresponse to a drop in pressure, which may be obtained in any suitableway, or by any suitable means, not herein shown and not of itselfforming part of my invention. I illustrate my invention as applied tothe problem of controlling the temperature of a volatile refrigerant asit is delivered by a compressor to a condenser and receiver. Where therefrigerator, or any part of the refrigerating cycle, is subjected tooutside, unheated air, the variations in the outside or ambienttemperature create problems. For example, the minimum outdoors ambienttemperature in parts of the United States may vary as much as F. or morefrom the maximuml outside ambient temperature. Such a iluctuation oftemperature, or even a smaller liuctuation, creates problems affectingthe flow of the hot gas from the compressor to the condenser. In thepast, attempts have been made to control the resultant pressureiluctuations by valving or restricting the flow of hot gas from thecompressor to the condenser. Any such valving or restricting presentspractical problems, and has disadvantages into which I need not go indetail.

By my invention, I maintain regulation of ow by keeping the refrigerantat a generally constant temperature,l

regardless of changes in ambient temperature. I may do this bymaintaining adequate heat exchange means in the line of ow of therefrigerant from the compressor to the condenser and by thermostaticallycontrolling such means. As an example of such means I illustrate theunit A in Figure 1, which is shown in greater detail in Figures 2 and 3.In the form shown in Figure 2, I illustrate a heat exchange casing, inthe form of an outer shell or cylinder Titi, having end closures 11 and12. The duct 6 delivers refrigerant, as at 6a, through the end 11 of thecylinder 1t), and the refrigerant is constrained to a tortuous andextended path, for example, by the spiral or helical vane 13.Refrigerant, after passing through the elongated passage thus formed,escapes, as at 6b, and ows toward the condenser.

While l do not wish to limit myself to any specic heat exchange means,except so far as I limit myself by specic limitations in my claims, Iillustrate in Figure 2 an inner axial passage or pipe 14 which extendsthrough the center of the helix 13 and which contains any suitable'resistance heater 15 connected by suitable conductive connections 15aand 15b to any suitable source of commerical current. The heater 15 maybe controlled in its operation by any suitable heat responsive controlmeans 16, shown in Figure 2 as extending into any suitable pipe 16aextending through the end 11 of the cylinder and through several of thebends of the helix. .Thus the operation of the heater 15 may becontrolled by a suitable heat responsive element, which, in turn,responds to the temperature of the refrigerant adjacent its entry intothe tortuous passage. formed by the helix 13. Any suitable outside layerof insulation may be employed, as at 17.

It will be realized that, whereas, I have described and illustrated apractical and operative device, nevertheless many changes may be made'in the size, shape, number and disposition of parts without departingfrom the spirit of my invention. -I therefore wish my description anddrawings to be `taken as in a broad sense illustrative or diagrammatic.For example, whereas I iind the hea-t exchange unit shown to be highlyadvantageous, I may obtain my result `by other heat exchange means. Whatis essential is that I provide means for heating the refrigerant, whennecessary, as it is delivered from the compressor to the condenser. Bycontrolling this heating elect in relation to or in response tovariations in ambient temperature, `I maintain Ian adequate uniformityof pressure conditions, and render `it unnecessary to valve or ltorestrict the flow Vof 'the refrigerant to the condenser and to thereceiver. Whereas the nature and position of the Vresistance 16 is`adequate and practical, it will be realized that 'I may employ heatresponsive means subjected to the movement of the refrigerant at anypoint bient temperature, I may, if I Wish, employ heat respon-V sivemeans directly subjected to variation inV outside ambient temperature.YIn'na broad sense,H my `invention contemplates varying l:the heatdeliveryl in'relation to or in director indirectresponse t-o changes-inoutside ambient` temperature. Looking at the problem from `a somewhatdifferent angle, I may say that the function ofthehat exchanger A intheY circuit, as shown in Figurel", is rather' to' prevent heatl'ossthan to add heat, or

to'sfu'perheat. The problem 'solved by my invention is notthatof`at`fecting'jcondenser pressure but, rather, that ofpreventingvariatons in ambient 'temperature from yale'cting condenserpressure.V heat' exchanger A, con'- trolledi'n response to variations in`ambient temperature, adds temperaturewlien necessary to prevent an'unfavorable drop inicondense'r pressure. Whereas I have illustrated myinvention as applied to control lthe flow of refrigerant from thedischarge side of the compressorV Vto the condenser, it will beunderstood that I may employ Vmy invention atk other points, wherenecessary, in the passes from compressor tocondenser, in controlledrelan tion to Variations of 'such ambient temperature.

2. The method of maintaining predetermined gas pressure in arefrigerating circuit, which includes heating the refrigerant, 'as itpasses from compressor to condenser,

and varying `such heat input to the refrigerant, in response.

. 4 sure discharge pipe extending `from the compressor to the condenser,a pipe extending from ythe condenser to the evaporator and a return pipeextending from the evaporator to the suction side ofthe compressor,Iand'V means for maintaining the temperature of the hot Agas deliveredfrom the compressor to the -condenser within a predetermined range,including heating means, and means `for maintaining said heating meansin he'at exchange relationship with the 'hot gas flowing from thecompressor tothe condenser. I

5. The structure of claim 4 characterized by and including `a lcontrolelement responsive to vthe temperature of hot gas.

6. The structure of claim 4 characterized by `and including a tortuouspassagermeans through which the hot gas Hows on its way yfrom thecompressor to vthe condenser, heating means eective to deliver heat -tothe gas as i-t ows through the tortuous passage means, andheatresponsive means for controlling the operation of the heating means,said heating-responsive means being adapted to respond `to thetemperatureof the hot gasV owing through the tortuous passage.v

7. A method of operating `a mechanical refrigerating clrcurt includingIa compressor, la condenser and anevaporator, in surroundings subjectedto substantial variationsV in `ambient temperature which includessensing ambient `temperature and supplying heat when needed, incontrolled response to lsaid sensing, tothe refrigerant Yas it passesfrom compressor to condenser, effec-tive to maintain a substantiallyuniform condenser pressure, `and thereby preventing undesired condenserpressure drops which might otherwise he caused by undue reduction ofYthe ambient `temperature to Which the refrigerating sys-V tem issubjected. f

References Cited in the le of this patent UNITED STATES PATENTS La PorteJune 16, 1953:V

